The efficiency of HFMI treatment and TIG remelting for extending the fatigue life of existing welded structures
Journal article, 2021

Different post‐weld treatment methods have been developed to enhance the fatigue strength of welded steel structures and extend the service lives of their components. High‐frequency mechanical impact (HFMI) treatment and tungsten inert gas (TIG) remelting are two methods that have attracted considerable interest in recent decades. This paper presents the results of a study of fatigue life extension for pre‐fatigued welded steel details which can be achieved using HFMI treatment and TIG remelting. More than 250 fatigue test results were collected – including different details such as butt welds, longitudinal attachments, transverse attachments and cover plate attachments. HFMI treatment was found to extend the life considerably when the specimens treated were free from cracks or when existing cracks were < 2.25 mm deep. TIG remelting could extend fatigue lives even with cracks > 4 mm deep. In comparison to TIG remelting, HFMI treatment results in a longer fatigue life extension for pre‐fatigued details, provided existing cracks are < 2.25 mm deep. Regarding TIG remelting, the depth of possible remaining cracks was found to be a substantial parameter when assessing the degree of life extension.

allowable crack size

analysis and design

TIG remelting


Steel bridges


high‐frequency mechanical impact

fatigue life extension


Hassan al-Karawi

Chalmers, Architecture and Civil Engineering, Structural Engineering

Mohammad al-Emrani

Chalmers, Architecture and Civil Engineering, Structural Engineering

Steel Construction

1867-0520 (ISSN) 1867-0539 (eISSN)

Vol. 14 2 95-106

LifeExt - Livslängdsförlängning för befintliga stålbroar

Swedish Transport Administration (TRV 2018/27547), 2018-05-15 -- 2020-11-30.

VINNOVA (2017-02670), 2017-06-08 -- 2019-12-31.

Driving Forces

Sustainable development

Subject Categories

Materials Engineering

Civil Engineering

Manufacturing, Surface and Joining Technology

Other Materials Engineering

Areas of Advance

Building Futures (2010-2018)

Materials Science


Chalmers Materials Analysis Laboratory



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